Telecommunications technologies have evolved dramatically in the course of the last decade, seeing analog transmission technologies, digital transmission technologies and more recently Internet Protocol (IP) based packet transmission technologies.
During the past years, the interest in using mobile telecommunications devices in day-to-day activities has increased. Traditionally, desktop computers, workstations, and other wireline computers allowed users to communicate, for example, via e-mail, instant messaging (IM) and chat. Nowadays, mobile devices, for example, mobile telephones, smartphones, handheld computers, personal digital assistants (PDAs) etc., also allow the users to communicate via e-mail, IM, chat and the like.
Mobile communications devices have evolved and are still evolving with the different transmission technologies that are being introduced. IP Multimedia Subsystems (IMS) is an IP based transmission technology that is currently being introduced into several markets. The introduction of the IMS technology does not go without difficulties. The hardware and communication protocols, for instance, differ from those of older technologies. This causes problems for interworking between the old and new technologies.
One of the problems concerns Session Initiation Protocol (SIP) sessions interworking of Open Mobile Alliance (OMA) Converged IP Messaging (CPM) and Short Message Service (SMS) (CPM-SMS), for allowing SMS user to be invited to participate in chat sessions.